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773 full-text articles. Page 1 of 17.

Design Of Orbital Maneuvers With Aeroassisted Cubesatellites, Stephanie Clark 2017 University of Arkansas, Fayetteville

Design Of Orbital Maneuvers With Aeroassisted Cubesatellites, Stephanie Clark

Stephanie Clark

Recent advances within the field of cube satellite technology has allowed for the possible development of a maneuver that utilizes a satellite's Low Earth Orbit (LEO) and increased atmospheric density to effectively use lift and drag to implement a noncoplanar orbital maneuver. Noncoplanar maneuvers typically require large quantities of propellant due to the large delta-v that is required. However, similar maneuvers using perturbing forces require little or no propellant to create the delta-v required. This research reported here studied on the effects of lift on orbital changes, those of noncoplanar types in particular, for small satellites without orbital maneuvering ...


Meso-Scale Imaging Of Composite Materials, Robert J. Grandin, Joseph N. Gray 2017 Iowa State University

Meso-Scale Imaging Of Composite Materials, Robert J. Grandin, Joseph N. Gray

Robert Grandin

The performance of composite materials is controlled by the interaction between the individual components as well as the mechanical characteristics of the components themselves. Geometric structure on the meso-scale, where the length-scales are of the same order as the material granularity, plays a key role in controlling material performance and having a quantitative means of characterizing this structure is crucial in developing our understanding of NDE technique signatures of early damage states. High-resolution computed tomography (HRCT) provides an imaging capability which can resolve these structures for many composite materials. Coupling HRCT with three-dimensional physics-based image processing enables quantitative characterization of ...


Implementation Of Automated 3d Defect Detection For Low Signal-To Noise Features In Nde Data, Robert J. Grandin, Joseph N. Gray 2017 Iowa State University

Implementation Of Automated 3d Defect Detection For Low Signal-To Noise Features In Nde Data, Robert J. Grandin, Joseph N. Gray

Robert Grandin

The need for robust defect detection in NDE applications requires the identification of subtle, low-contrast changes in measurement signals usually in very noisy data. Most algorithms rarely perform at the level of a human inspector and often, as data sets are now routinely 10+ Gigabytes, require laborious manual inspection. We present two automated defect segmentation methods, simple threshold and a binomial hypothesis test, and compare effectiveness of these approaches in noisy data with signal to noise ratios at 1:1. The defect-detection ability of our algorithm will be demonstrated on a 3D CT volume, UT C-scan data, magnetic particle images ...


Inversion Of Eddy Current Probe Impedance Data For Crack Reconstruction, John Bowler, D. J. Harrison, S. J. Norton 2017 University of Surrey

Inversion Of Eddy Current Probe Impedance Data For Crack Reconstruction, John Bowler, D. J. Harrison, S. J. Norton

John R. Bowler

The aim of eddy current inversion is to reconstruct an unknown flaw from probe signals measured as a function of probe position and frequency or time. In seeking the solution of an inverse problem, one can take advantage of an ability to solve forward problems by using predictions of probe signals calculated with a tentative estimate of the flaw. A well known inversion strategy adopted here for eddy current inversion, is that of varying the flaw estimate iteratively until the disparity between predicted and observed probe signals is minimized. Then the model flaw which gives the optimum predictions of the ...


Study Of Knowledge-Based System (Kbs) And Decision Making Methodologies In Materials Selection For Lightweight Aircraft Metallic Structures, Pashupati R. Adhikari, Reza Mirshams 2017 University of North Texas

Study Of Knowledge-Based System (Kbs) And Decision Making Methodologies In Materials Selection For Lightweight Aircraft Metallic Structures, Pashupati R. Adhikari, Reza Mirshams

Journal of Applied Science & Engineering Technology

This paper presents an overview of knowledge-based system (KBS) in the context of decision making methodologies used in materials selection for the design of light weight aircraft metallic structures. Overall aircraft weight reduction means substantially less fuel consumption and better efficiency. Part of the solution to this problem is to find a way to reduce overall weight of metallic structures in the aircraft. Two distinct multiple criteria decision making (MCDM) methodologies are presented with examples featuring a set of short-listed materials suitable in the design of the structures. Pre-defined constraint values, mainly mechanical properties, are employed as relevant attributes satisfying ...


Study Of Custom Tool Control In Aviation And Aerospace And Selection Of Materials And Manufacturing Process, Ethan C. Rowley 2017 Morehead State University

Study Of Custom Tool Control In Aviation And Aerospace And Selection Of Materials And Manufacturing Process, Ethan C. Rowley

Theses and Dissertations

A thesis presented to the faculty of the College of Business and Technology at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Science by Ethan C. Rowley on April 27, 2017.


Ultrasonic Sol-Gel Arrays For Monitoring High-Temperature Corrosion, Thomas J. Eason, Leonard J. Bond, Mark G. Lozev 2017 Iowa State University

Ultrasonic Sol-Gel Arrays For Monitoring High-Temperature Corrosion, Thomas J. Eason, Leonard J. Bond, Mark G. Lozev

Leonard J. Bond

Corrosion of oil refinery equipment operating at high temperature is a growing challenge linked to an increase in sulfur concentration and acidity within the world supply of crude oils. Improved high temperature monitoring tools are needed to continuously measure the local minimum wall thickness of steel pipe subject to non-uniform internal corrosion. Thickness measurements must be sufficiently accurate to calculate the maximum allowable stress permissible as to avoid failure. Thickness measurements must also be sufficiently reliable and precise to correlate the rate of wall-loss with process conditions as to improve future corrosion rate predictions. Permanently installed structural health monitoring (SHM ...


Ultrasonic Scattering From Ahemispherical Pit Theory And Experimentalmeasurement Precision, Thomas J. Eason, Leonard J. Bond, Mark G. Lozev 2017 Iowa State University

Ultrasonic Scattering From Ahemispherical Pit Theory And Experimentalmeasurement Precision, Thomas J. Eason, Leonard J. Bond, Mark G. Lozev

Leonard J. Bond

The accuracy and precision of ultrasonic thickness measurement systems are influenced by systematic and environmental factors including the back-wall reflection surface profile. The scattering amplitude from a relatively flat and smooth back-wall surface can be characterized by the acoustic impedance ratio of the two materials at the interface. If the back-wall surface increases in roughness due to internal corrosion, then the arrival time of the incident wave upon the various surface heights will be slightly different, resulting in slight phase changes within the reflected field. In addition, the roughness of the internal surface will result in various impingement anglesrelative to ...


Variable Input Space Observer For Structural Health Monitoring Of High-Rate Systems, Jonathan Hong, Simon Laflamme, Jacob Dodson 2016 Iowa State University

Variable Input Space Observer For Structural Health Monitoring Of High-Rate Systems, Jonathan Hong, Simon Laflamme, Jacob Dodson

Simon Laflamme

Some engineering systems experiencing high-rate dynamic events, including air bags, debris detection, and active blast protection systems, could benefit from high-rate real-time observers for enhanced performance. However, the task of high-rate state estimation is challenging, in particular for real-time applications where the rate of the observer’s convergence needs to be in the microsecond range. This paper discusses critical challenges in designing highrate observers, and argues that adaptive observers are promising at the task of state estimation, and that they could be applied at high-rates provided the development of strategies to substantially increase their convergence. A novel adaptive observer termed ...


Cubesat Adcs Validation And Testing Apparatus, Jacob Stevens 2016 Western Michigan University

Cubesat Adcs Validation And Testing Apparatus, Jacob Stevens

Honors Theses

The WALI team at Western Michigan University requested a test environment to validate their CubeSat’s de-tumbling control system and hardware. The test environment required a Helmholtz cage and spherical air bearing. The Helmholtz cage provides an adjustable magnetic field to simulate low earth orbit; the spherical air bearing simulates the friction free environment the CubeSat will experience in space. In conjunction, the two components create an adjustable system that simulates a satellite in low earth orbit.


Microstructural Analysis Of Thermoelastic Response, Nonlinear Creep, And Pervasive Cracking In Heterogeneous Materials, Alden C. Cook 2016 University of Maine

Microstructural Analysis Of Thermoelastic Response, Nonlinear Creep, And Pervasive Cracking In Heterogeneous Materials, Alden C. Cook

Electronic Theses and Dissertations

This dissertation is concerned with the development of robust numerical solution procedures for the generalized micromechanical analysis of linear and nonlinear constitutive behavior in heterogeneous materials. Although the methods developed are applicable in many engineering, geological, and materials science fields, three main areas are explored in this work. First, a numerical methodology is presented for the thermomechanical analysis of heterogeneous materials with a special focus on real polycrystalline microstructures obtained using electron backscatter diffraction techniques. Asymptotic expansion homogenization and finite element analysis are employed for micromechanical analysis of polycrystalline materials. Effective thermoelastic properties of polycrystalline materials are determined and compared ...


Development Of Cal Poly's Shock Table, Christopher D. Risner 2016 California Polytechnic State University - San Luis Obispo

Development Of Cal Poly's Shock Table, Christopher D. Risner

Master's Theses and Project Reports

Shock is one of the environmental tests that a spacecraft must pass before being cleared for launch. Shock testing poses a challenging data acquisition issue and careful selection of equipment is crucial to creating a successful shock test facility. Cal Poly’s CubeSat programs can currently perform all environmental testing other than shock themselves, so a quality shock table would be useful. Previous groups of students had developed a shock table, and this paper details the improvement and characterization of that shock table’s behavior. Several adjustable parameters were tested and documented to discover trends in the shock table’s ...


Nanostructured Morphologies In Glassy Polymer Networks, Brian Greenhoe 2016 University of Southern Mississippi

Nanostructured Morphologies In Glassy Polymer Networks, Brian Greenhoe

Dissertations

The body of this work describes a novel approach for the dispersion of multi-walled carbon nanotubes in a high Tg epoxy prepolymer matrix using a twin screw high-shear continuous reactor. The method demonstrated improves on previous dispersion methods in several ways. It offers increased efficiency through excellent heat transfer, while being solvent-less, scale-able, and tailorable to drive dispersion states to judiciously chosen dispersion states. Furthermore, it was shown that dispersion state and agglomerate morphology can be directed, in several ways, through processing conditions and also by controlling the matrix viscosity profile through cure. Broadband dielectric spectroscopy, optical hot-stage microscopy ...


Senior Design - Hybrid Rocket Conceptual Design, Hardeo Chin 2016 Selected Works

Senior Design - Hybrid Rocket Conceptual Design, Hardeo Chin

Hardeo Chin

Hybrid rockets utilize rocket motors which contain both liquid and solid propellant. They provide numerous benefits compared to solid and liquid rockets such as being mechanically simpler, having denser fuels, and providing higher specific impulse. Generally, the oxidizer is liquid and fuel is solid because solid oxidizers are dangerous and are lower performing than their liquid counterparts. Hybrid systems avoid the significant hazards of manufacturing, shipping, and handling that solid rocket motors possess. The conceptual design report herein separately assesses the structural and propulsive needs for a mid-power rocket with a G-motor


Simulation Investigation Of Temperature Distribution In Large Aluminium Panel During Autoclave Age Forming Process, Yongqian Xu 2016 Central South University

Simulation Investigation Of Temperature Distribution In Large Aluminium Panel During Autoclave Age Forming Process, Yongqian Xu

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.


Multi-Dome Forming Of A Ti–Al–Mn Alloy, Sergey Aksenov, Aleksey Kolesnikov, Ivan Zakhariev 2016 National Research University Higher School of Economics

Multi-Dome Forming Of A Ti–Al–Mn Alloy, Sergey Aksenov, Aleksey Kolesnikov, Ivan Zakhariev

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.


Forensic Examination Using A Nondestructive Evaluation Method For Surface Metrology, David J. Eisenmann, L. Scott Chumbley 2016 Iowa State University

Forensic Examination Using A Nondestructive Evaluation Method For Surface Metrology, David J. Eisenmann, L. Scott Chumbley

David Eisenmann

The objective of this paper is to describe the use of a new technique of optical profilometry in a nondestructive, non‐contact fashion for the comparison of two metallic surfaces, one hard and one soft. When brought in contact with one another, the harder material (i.e. the tool) will impress its surface roughness onto the softer. It is understood that the resulting set of impressions left from a tool tip act in a manner similar to a photographic negative, in that it leaves a reverse, or negative impression on the surface of a plate. If properly inverted and reversed ...


Quantification Of Toolmarks, L. Scott Chumbley, David J. Eisenmann, M. Morris, S. Zhang, J. Kreiser, J. Craft, C. Fisher 2016 Iowa State University

Quantification Of Toolmarks, L. Scott Chumbley, David J. Eisenmann, M. Morris, S. Zhang, J. Kreiser, J. Craft, C. Fisher

David Eisenmann

No abstract provided.


Synthetic Defects For Vibrothermography, Jeremy Blake Renshaw, Stephen D. Holland, R. Bruce Thompson, David J. Eisenmann 2016 Iowa State University

Synthetic Defects For Vibrothermography, Jeremy Blake Renshaw, Stephen D. Holland, R. Bruce Thompson, David J. Eisenmann

David Eisenmann

Synthetic defects are an important tool used for characterizing the performance of nondestructive evaluation techniques. Viscous material‐filled synthetic defects were developed for use in vibrothermography (also known as sonic IR) as a tool to improve inspection accuracy and reliability. This paper describes how the heat‐generation response of these VMF synthetic defects is similar to the response of real defects. It also shows how VMF defects can be applied to improve inspection accuracy for complex industrial parts and presents a study of their application in an aircraft engine stator vane.


Flourescent Penetrant Inspection—Cleaning Study Update, David J. Eisenmann, Lisa H. Brasche 2016 Iowa State University

Flourescent Penetrant Inspection—Cleaning Study Update, David J. Eisenmann, Lisa H. Brasche

David Eisenmann

Fluorescent penetrant inspection (FPI) is widely used in the aviation industry and other industries for surface‐breaking crack detection. As with all inspection methods, adherence to the process parameters is critical to the successful detection of defects. There is variety of lubricants and surface coatings used in the aviation industry which must be removed prior to FPI. Before the FPI process begins, components are cleaned using a variety of cleaning methods which are selected based on the alloy and the soil types which must be removed. It is also important that the cleaning process not adversely affect the FPI process ...


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